PFIZERPEN

Buffered Pfizerpen (Penicillin G Potassium for Injection, USP) is a sterile, pyrogen-free powder for reconstitution. Buffered Pfizerpen for Injection is an antibacterial agent for intramuscular, continuous intravenous infusion, intrapleural or other local infusion, and intrathecal administration. Each million units contains approximately 6.8 milligrams of sodium (0.3 mEq) and 65.6 milligrams of potassium (1.68 mEq). Buffered Pfizerpen (Penicillin G Potassium for Injection, USP) is supplied in vials equivalent to 5,000,000 units (5 million units) or 20,000,000 units (20 million units) of penicillin G as the potassium salt. Chemically, Pfizerpen is monopotassium 3,3-dimethyl-7-oxo-6-(2-phenylacetamido)-4-thia-1-azabicyclo (3.2.0) heptane-2-carboxylate. It has a molecular weight of 372.48 and the following chemical structure: Formula C 16 H 17 KN 2 O 4 S Penicillin G potassium is a colorless or white crystal, or a white crystalline powder which is odorless, or practically so, and moderately hygroscopic. Penicillin G potassium is very soluble in water. The pH of the reconstituted product is between 6.0–8.5. Chemical Structure

Therapy Penicillin G Potassium for Injection is indicated in the treatment of serious infections caused by susceptible strains of the designated microorganisms in the conditions listed below. Appropriate culture and susceptibility tests should be done before treatment in order to isolate and identify organisms causing infection and to determine their susceptibility to penicillin G. Therapy with Penicillin G Potassium for Injection may be initiated before results of such tests are known when there is reason to believe the infection may involve any of the organisms listed below; however, once these results become available, appropriate therapy should be continued. CLINICAL INDICATION INFECTING ORGANISM Septicemia, empyema, pneumonia, pericarditis, endocarditis, meningitis Streptococcus pyogenes (group A β-hemolytic streptococcus), other β-hemolytic streptococci including groups C, H, G, L and M, Streptococcus pneumoniae and Staphylococcus species (non-penicillinase producing strains) Anthrax Bacillus anthracis Actinomycosis (cervico-facial disease and thoracic and abdominal disease) Actinomyces israelii Botulism (adjunctive therapy to antitoxin), gas gangrene, and tetanus (adjunctive therapy to human tetanus immune globulin) Clostridium species Diphtheria (adjunctive therapy to antitoxin and prevention of the carrier state) Corynebacterium diphtheriae Erysipelothrix endocarditis Erysipelothrix rhusiopathiae Fusospirochetosis (severe infections of the oropharynx [Vincent's], lower respiratory tract and genital area) Fusobacterium species and spirochetes Listeria infections including meningitis and endocarditis Listeria monocytogenes Pasteurella infections including bacteremia and meningitis Pasteurella multocida Haverhill fever Streptobacillus moniliformis Rat bite fever Spirillum minus or Streptobacillus moniliformis Disseminated gonococcal infections Neisseria gonorrhoeae (Penicillin-susceptible) Syphilis (congenital and neurosyphilis) Treponema pallidum Meningococcal meningitis and/or septicemia Neisseria meningitidis Gram-negative bacillary infections (bacteremias) Penicillin G is not the drug of choice in the treatment of Gram-negative bacillary infections. Gram-negative bacillary organisms ( i.e . Enterobacteriaceae) To reduce the development of drug-resistant bacteria and maintain effectiveness of Penicillin G Potassium and other antibacterial drugs, Penicillin G Potassium should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy.

Buffered Penicillin G Potassium for Injection, USP may be given intravenously or intramuscularly. The usual dose recommendations are as follows: Adult patients CLINICAL INDICATION DOSAGE Serious infections due to susceptible strains of streptococci (including S. pneumoniae ) -septicemia, empyema, pneumonia, pericarditis, endocarditis and meningitis 12 to 24 million units/day depending on the infection and its severity administered in equally divided doses every 4–6 hours. Serious infections due to susceptible strains of staphylococci -septicemia, empyema, pneumonia, pericarditis, endocarditis and meningitis 5 to 24 million units/day depending on the infection and its severity administered in equally divided doses every 4–6 hours. Anthrax Minimum of 8 million units/day in divided doses every 6 hours. Higher doses may be required depending on susceptibility of organism. Actinomycosis Cervicofacial disease Thoracic and abdominal disease 1 to 6 million units/day Because of its short half-life, Penicillin G is administered in divided doses, usually every 4–6 hours with the exception of meningococcal meningitis/septicemia, i.e. , every 2 hours. 10 to 20 million units/day Clostridial infections Botulism (adjunctive therapy to antitoxin) Gas gangrene (debridement and/or surgery as indicated) Tetanus (adjunctive therapy to human tetanus immune globulin) 20 million units/day Diphtheria (adjunctive therapy to antitoxin and for the prevention of the carrier state) 2 to 3 million units/day in divided doses for 10–12 days Erysipelothrix endocarditis 12 to 20 million units/day for 4–6 weeks Fusospirochetosis (severe infections of the oropharynx [Vincent's], lower respiratory tract and genital area) 5 to 10 million units/day Listeria infections Meningitis Endocarditis 15 to 20 million units/day for 2 weeks 15 to 20 million units/day for 4 weeks Pasteurella infections including bacteremia and meningitis 4 to 6 million units/day for 2 weeks Haverhill fever; Rat-bite fever 12 to 20 million units/day for 3–4 weeks Disseminated gonococcal infections, such as meningitis, endocarditis, arthritis, etc., caused by penicillin – susceptible organisms 10 million units/day ; duration depends on the type of infection Syphilis (neurosyphilis) 12 to 24 million units/day, as 2–4 MU every 4 hours for 10–14 days; many experts recommend additional therapy with Benzathine PCN G 2.4 MU IM weekly for 3 doses after completion of IV therapy Meningococcal meningitis and/or septicemia 24 million units/day as 2 million units every 2 hours Pediatric patients This product should not be administered to patients requiring less than one million units per dose (see Precautions-Pediatric Use ). CLINICAL INDICATION DOSAGE Serious infections, such as pneumonia and endocarditis, due to susceptible strains of streptococci (including S. pneumoniae ) and meningococcus 150,000–300,000 units/kg/day divided in equal doses every 4–6 hours; duration depends on infecting organism and type of infection Meningitis caused by susceptible strains of pneumococcus and meningococcus 250,000 units/kg/day divided in equal doses every 4 hours for 7–14 days depending on the infecting organism (maximum dose of 12–20 million units/day) Disseminated Gonococcal Infections (penicillin-susceptible strains) Weight less than 45 kg: Arthritis 100,000 units/kg/day in 4 equally divided doses for 7–10 days Meningitis 250,000 units/kg/day in equal doses every 4 hours for 10–14 days Endocarditis 250,000 units/kg/day in equal doses every 4 hours for 4 weeks Arthritis, meningitis, endocarditis Weight 45 kg or greater: 10 million units/day in equally divided doses with the duration of therapy depending on the type of infection Syphilis (congenital and neurosyphilis) after the newborn period 200,000–300,000 units/kg/day (administered as 50,000 units/kg every 4–6 hours) for 10–14 days Diphtheria (adjunctive therapy to antitoxin and for prevention of the carrier state) 150,000–250,000 units/kg/day in equal doses every 6 hours for 7–10 days Rat-bite fever; Haverhill fever (with endocarditis caused by S. moniliformis ) 150,000–250,000 units/kg/day in equal doses every 4 hours for 4 weeks Renal Impairment Penicillin G is relatively nontoxic, and dosage adjustments are generally required only in cases of severe renal impairment. The recommended dosage regimens are as follows: Creatinine clearance less than 10 mL/min/1.73m 2 ; administer a full loading dose (see recommended dosages in the tables above) followed by one-half of the loading dose every 8–10 hours. Uremic patients with a creatinine clearance greater than 10 mL/min/1.73m 2 ; administer a full loading dose (see recommended dosages in the tables above) followed by one-half of the loading dose every 4–5 hours. Additional dosage modification should be made in patients with hepatic disease and renal impairment. For most acute infections, treatment should be continued for at least 48 to 72 hours after the patient becomes asymptomatic. Antibiotic therapy for Group A β-hemolytic streptococcal infections should be maintained for at least 10 days to reduce the risk of rheumatic fever. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit. Reconstitution The following table shows the amount of solvent required for solution of various concentrations: Approx. Desired Concentration (units/mL) Volume (mL) Solvent for Vial of 5,000,000 units Infusion Only Volume (mL) Solvent for Vial of 20,000,000 units 50,000 – – 100,000 – – 250,000 18.2 75.0 500,000 8.2 33.0 1,000,000 3.2 11.5 When the required volume of solvent is greater than the capacity of the vial, the penicillin can be dissolved by first injecting only a portion of the solvent into the vial, then withdrawing the resultant solution and combining it with the remainder of the solvent in a larger sterile container. Buffered Pfizerpen (Penicillin G Potassium for Injection, USP) is highly water soluble. It may be dissolved in small amounts of Water for Injection, or Sterile Isotonic Sodium Chloride Solution for Parenteral Use. All solutions should be stored in a refrigerator. When refrigerated, penicillin solutions may be stored for seven days without significant loss of potency. Buffered Pfizerpen for Injection may be given intramuscularly or by continuous intravenous infusion for dosages of 500,000, 1,000,000, or 5,000,000 units. It is also suitable for intrapleural, intraarticular, and other local instillations. THE 20,000,000 UNIT DOSAGE MAY BE ADMINISTERED BY INTRAVENOUS INFUSION ONLY. (1) Intramuscular Injection Keep total volume of injection small. The intramuscular route is the preferred route of administration. Solutions containing up to 100,000 units of penicillin per mL of diluent may be used with a minimum of discomfort. Greater concentration of penicillin G per mL is physically possible and may be employed where therapy demands. When large dosages are required, it may be advisable to administer aqueous solutions of penicillin by means of continuous intravenous infusion. (2) Continuous Intravenous Infusion Determine the volume of fluid and rate of its administration required by the patient in a 24 hour period in the usual manner for fluid therapy, and add the appropriate daily dosage of penicillin to this fluid. For example, if an adult patient requires 2 liters of fluid in 24 hours and a daily dosage of 10 million units of penicillin, add 5 million units to 1 liter and adjust the rate of flow so the liter will be infused in 12 hours. (3) Intrapleural or Other Local Infusion If fluid is aspirated, give infusion in a volume equal to ¼ or ½ the amount of fluid aspirated, otherwise, prepare as for intramuscular injection. (4) Intrathecal Use The intrathecal use of penicillin in meningitis must be highly individualized. It should be employed only with full consideration of the possible irritating effects of penicillin when used by this route. The preferred route of therapy in bacterial meningitides is intravenous, supplemented by intramuscular injection. Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. Sterile solution may be left in refrigerator for one week without significant loss of potency.

A history of a hypersensitivity (anaphylactic) reaction to any penicillin is a contraindication.

Body as a whole The Jarisch-Herxheimer reaction is a systemic reaction that may occur after the initiation of penicillin therapy in patients with syphilis or other spirochetal infections ( i.e ., Lyme disease and Relapsing fever). The reaction begins one or two hours after initiation of therapy and disappears within 12 to 24 hours. It is characterized by fever, chills, myalgias, headache, exacerbation of cutaneous lesions, tachycardia, hyperventilation, vasodilation with flushing and mild hypotension. The pathogenesis of the Herxheimer reaction may be due to the release from the spirochetes of heat-stable pyrogen. Hypersensitivity reactions The reported incidence of allergic reactions to all penicillins ranges from 0.7 to 10 percent in different studies (see Warnings ). Sensitization is usually the result of previous treatment with a penicillin, but some individuals have had immediate reactions when first treated. In such cases, it is postulated that prior exposure to penicillin may have occurred via trace amounts present in milk or vaccines. Two types of allergic reactions to penicillin are noted clinically – immediate and delayed. Immediate reactions usually occur within 20 minutes of administration and range in severity from urticaria and pruritus to angioneurotic edema, laryngospasm, bronchospasm, hypotension, vascular collapse and death (see Warnings ). Such immediate anaphylactic reactions are very rare and usually occur after parenteral therapy, but a few cases of anaphylaxis have been reported following oral therapy. Another type of immediate reaction, an accelerated reaction, may occur between 20 minutes and 48 hours after administration and may include urticaria, pruritus, fever and, occasionally, laryngeal edema. Delayed reactions to penicillin therapy usually occur within 1–2 weeks after initiation of therapy. Manifestations include serum sickness-like symptoms, i.e., fever, malaise, urticaria, myalgia, arthralgia, abdominal pain and various skin rashes, ranging from maculopapular eruptions to exfoliative dermatitis. Contact dermatitis has been observed in individuals who prepare penicillin solutions. Gastrointestinal system Pseudomembranous colitis has been reported with the onset occurring during or after penicillin G treatment. Nausea, vomiting, stomatitis, black or hairy tongue, and other symptoms of gastrointestinal irritation may occur, especially during oral therapy. Hematologic system Reactions include neutropenia, which resolves after penicillin therapy is discontinued; Coombs-positive hemolytic anemia, an uncommon reaction, occurs in patients treated with intravenous penicillin G in doses greater than 10 million units/day and who have previously received large doses of the drug; and with large doses of penicillin, a bleeding diathesis can occur secondary to platelet dysfunction. Metabolic Penicillin G Potassium for Injection (1 million units contains 1.68 mEq of potassium ion) may cause serious and even fatal electrolyte disturbances, i.e ., hyperkalemia, when given intravenously in large doses. Nervous system Neurotoxic reactions including hyperreflexia, myoclonic twitches, seizures and coma have been reported following the administration of massive intravenous doses, and are more likely in patients with impaired renal function. Urogenital system Renal tubular damage and interstitial nephritis have been associated with large intravenous doses of penicillin G. Manifestations of this reaction may include fever, rash, eosinophilia, proteinuria, eosinophiluria, hematuria and a rise in serum urea nitrogen. Discontinuation of penicillin G results in resolution in the majority of patients. Local reactions Phlebitis and thrombophlebitis may occur, and pain at the injection site has been reported with intravenous administration. To report SUSPECTED ADVERSE EVENTS, contact ( insert name of manufacturer ) at ( insert manufacturer's phone number ) or FDA at 1-800-FDA-1088 or http://www.fda.gov/ for voluntary reporting of adverse reactions.

Bacteriostatic antibacterials ( i.e ., chloramphenicol, erythromycins, sulfonamides or tetracyclines) may antagonize the bactericidal effect of penicillin, and concurrent use of these drugs should be avoided. This has been documented in vitro ; however, the clinical significance of this interaction is not well-documented. Penicillin blood levels may be prolonged by concurrent administration of probenecid which blocks the renal tubular secretion of penicillins. Other drugs may compete with penicillin G for renal tubular secretion and thus prolong the serum half-life of penicillin. These drugs include: aspirin, phenylbutazone, sulfonamides, indomethacin, thiazide diuretics, furosemide and ethacrynic acid.

Store the dry powder below 86°F (30°C).